Step one: Warm up
Warm-up is an important stage - don't even think about skipping it, you'll regret it tomorrow!
Do this for five minutes
Exercise one: Squats
Stand with your feet hip distance apart with your toes, knees and hips in a straight line. Slowly lower your body as if you're sitting in a chair, to a 90 degree angle, or whatever you can manage. Slowly stand back up, but don't lock your knees.
Exercise two: Lunges
Stand with your legs together then lunge forward with your left leg. As you do that, bend your knee in your right leg so it nearly touches the floor. Move back to your start position then do the same with your right leg.
Exercise three: Running on the spot
First, run on the spot in the usual way. Then, run on the spot trying to touch your bum with your heels.